Pixound brings an intriguing approach to the music app: letting you play any photo as if it were a musical instrument. That was enough to get our attention, and when we first started playing around with the Pixound app for iOS ($1), we thought it was a neat gimmick, but probably not worth a buck.

Then we kept playing, delving deeper into the app's features. Having done so, we think this one's definitely worth a dollar. At the very least, you could use it to take a picture of the people sitting across from you on the subway, and start playing them like a musical instrument.

Due to the odd economics of apps, that ability - something nobody in their right mind would design dedicated hardware for - costs about a fifth of the price of an super-expensive cup of coffee.

Pixound's mojo runs way deeper than just pulling off that subway stunt though. In its default mode, the app lets you play colors (pictured left) using a piano sound, but it also contains every musical mode you can think of, a wide variety of instruments (all of which sound great), a backing drum track, and even the ability to tweak how the app lets you play the various colors in your photos (RGB or hue).

Oh, and it also comes with variable chorus and reverb, presets that make everything sound good without you futzing around, and pre-stocked photos with their designs processed to work well within the app (like the one to the right). Pixound also includes a ball that can move from left to right or in loops through a painting, basslines, and, frankly, too many options to include here.

And yes, you can import any photo from your iPhone or other iOS device and play that too.

The interface responds quickly to the touch, despite the complexity of how the sounds are generated. There's no AirPlay, so you can't play photos on your television set via Apple TV, which would be nice, but that omission is to be expected, because AirPlay wasn't designed to stream sounds that are always changing. And clearly, the app should let you record and share music, which it doesn't.

Still, after reading this far, you probably already know whether you want this app or not. And you probably do.

Here are some more screenshots showing a bit more of what is possible with Pixound: